In recent years the use of metallic doors and metallic door frames, particularly in industrial and commerical construction has greatly increased. For examples, for safety reasons, most hospitals, nursing homes and the like utilize metallic doors which serve as fire barriers.
Often during construction, the frameworks for the metallic doors are positioned in the field shortly after construction has begun. In fact, this is often done prior to the installation of any floors, shortly after the footers have been constructed for either the perimeter walls or the interior bearing walls.
When using wooded doors, including wooden pre-hung door assemblies, if the door framing is improperly installed, it is normally relatively easy to correct the defect. For example, if the vertical jambs of the frame are installed in a non-parallel position or in a position wherein at least one of the frames is not in a vertical plane, it is usually possible with wooden door assemblies to shim the entire structure so that the door itself can be properly installed. Similarly, if the installed door frame is not rectangular, it is often possible to plane one edge of the door and to realign the hinges so that the door will fit within the frame.
Unfortunately, it is very difficult to properly install a metal door if the metallic door frame has been improperly installed. Because of the normal construction practice of installing the metallic frame early during the construction process, the door frame is very easily misaligned during the construction process, for example, when the masonry or concrete walls are installed adjacent the door frame. When this occurs, the metallic door will not fit within the door frame and it is difficult to make a correction in the field. If there is only a slight misalignment, in the past, the metallic door has been ground to enable its installation or, for example, some tolerances are provided by bending or adjusting the hinges. However, these are field expediences and the installed assembly is often less than desirable in the final building construction. If the alignment of the metallic door frames is too great, it is sometimes necessary to install an undersized door in the frame. Again, the final assembly does not give the performance that it should in the completed building. In the past, inspectors and architects have had little choice in allowing these types of field expedients. The alternative was to tear down and bebuild at least a portion of the wall surrounding the metallic door frame so that the frame could be reinstalled in a proper manner.